Fluid pressure actuator



Aug. 9, 1949. E. R. HTCH 2,41 ,575

FLUID PRESSURE ACTUATOR Filed Dec. 9, 1944 Sheets-Sheet l INVENTOR.

A TTOPNEVS Aug. 9, 1949. E. R. FITCH FLUID PRESSURE ACTUATOR 2 Sheets-Sheet 2 FiledDec. 9, 1944 qlmlll plan J INVENTOR.

Ell li. Far/L BY r A TTDPNEYS Patented Aug. 9, 1949 FLUID PRESSURE ACTUATOR Ellery R. Fitch, Elyria, Ohio, assignor to Bendix- I Westinghouse Automotive Air Brake Company, Elyria, Ohio, a corporation of Delaware Application December 9, 1944, Serial No. 567,387

14 Claims.

This invention relates to fluid pressure actuators. and more particularly to actuators of the so-called diaphragm type adapted to actuate vehicle brakes and similar devices.

Fluid pressure actuators of the diaphragm type have previously been in common use for the operation of brakes, but the construction of many of these actuators has been such that the outside diameter of the actuator has been excessive in comparison to the effective diameter of the diaphragm, and it is accordingly an object of the present invention to provide a fluid pressure actuator of the diaphragm type so constructed as to overcome this difficulty.

Another object of the present invention is to provide, in a fluid pressure actuator of the above type, means for retaining the diaphragm in the actuator, so constituted as to facilitate ready assembly of the actuator.

Yet another object of the invention is to provide, in a fluid pressure actuator of the above type, novel means for attaching the diaphragm to the casing of the'actuator.

Still another object of the invention is to provide, in an actuator of the above type, means for retaining the diaphragm in the casing of the actuator, so constituted as to insure equalization of the stresses of. the various portions of the diaphragm.

A still further object of the invention is to provide means for mounting a diaphragm in an actuator so constituted as to prevent or minimize leakage of fluid from the actuator.

The above and other objects of the inventio will appear more fully hereinafter from the following description when taken in connection with the accompanying drawing, wherein one form of the present invention is illustrated. It is to be expressly understood, however, that the draw ings are utilized for purposes of illustration only, and are not designed as a definition of the limits of the invention, reference being bad for this purpose to the appended claims.

In the drawings, wherein similar reference characters are utilized to denote similar parts in the different views;

Fig. 1 is an illustration, partially in section, of an actuator assembly constructed in accordance with the principles of the present invention;

Fig. 2 is a view, partially in cross section, of the diaphragm utilized in the actuator shown in Fig. 1 and Fig. 3 is an end view of the diaphragm shown in Fig. 2-.

Referring more particularly to Fig. 2, a dia- UNITED STATES PATENT orrics:

phragm l is shown, closed at" itsright :end by means of a wall 5, and provided "at' its left end with a plurality of outwardly extending lugs 6, each provided with a bore I as showmjfor reasons to be more fully described hereinafter. A portion of the diaphragm is provided with an annular fabric reinforcement 8, and while inthe drawing, this fabric is shown as extending through only a portion of the diaphragm, it"willbe' understood that if desired, the fabric may be extended in either direction from the position shown in order to more fully reinforce the diaphragm. The diaphragm is formed of rubber or other similar flexible material, and is preferably molded in the form shown in Figs. 2 and 3, the annular fabric reinforcement being embedded inthe rubber in a manner well known to those skilled in the art.

Referring now to Fig. 1, the actuator is provided with a cylindrical casing 9, theport'ion IU of the casing serving to close the left end, and being provided with a port ll adapted to receive fluid pressure from any suitable source, not shown. When the diaphragm is installed, it is turned inside out, whereupon the lugs 6 assume an inwardly extending position similar to that shown in Fig. 1. An annular clamping ring [2 is inserted between the inner surface of the lugs and the end wall of the diaphragm when the latter is turned inside out, and this ring isprovided with a plurality of studs l3 which are welded or otherwise rigidly attached to the annular ring, these studs being adapted to register with corresponding bores I4 formed in the. left end of the casing and circularly disposed as shown. The studs on the clamping ring are inserted through the holes I in thelugs before the diaphragm is inserted in the casing, and'when the diaphragm is inserted, the studs are pushed through the bores I4, and nuts l5 are then threaded on to the studs in order to draw the annular ring to the left toward the inner end of the casing. This serves to compress the lugs between the ring and the casing and the degree of this compression is limited by an annular stop l6 formed on the left end of the ring. The ring I2 is also provided with a portion I! which is adapted on movement to the left to clamp an annular portion I 8 of the diaphragm against a tapered surface I!) extending inwardly to the left from the main portion of the cylindrical casing wall. The portion l8 of the diaphragm is continuous throughout the circumference of the diaphragm, and consequently this clamping action serves to prevent leakage of air between the outer surface of the diaphragm and the inner surface of the casing. It will thus be understood, that insertion of the studs through the holes I in the diaphragm prior to assembly of the latter with the casing insures proper positioning of the portion I! of the annular ring with respect to the portion ll of the diaphragm to insure uniform clamping of the diaphragm between the ring and the wall portion I! of the casing throughout its entire circumference, the studs thus serving to definitely locate the diaphragm prior to the assembly of the latter in the casing.

In order that the diaphragm maybe effective to operate the brakes or any similar device, a cup shaped follower 20 is rigidly attached to the left end of the push rod 2| by riveting or other suitable means, this follower being of slightly smaller diameter than the interior of the casing.

in order to permit the diaphragm to take the form of a U shaped annular ring as shown. The right end of the casing is closed by means of a cover plate 22 inserted in the end of the housing and maintained in this position by means of a suitable cap screw 23. The cup shaped follower is normally maintained in the position shown adjacent to the left end of the casingby means of a return spring 24 interposed between the right surface of the follower and the left surface of the cover plate 22, an enlarged bore 25 centrally located in the cover plate 22 serving to permit movement of the push rod therethrough and limited angular movement of the push rod with respect to the center line of the casing.

When fluid pressure is admitted to the left end of the casing through the port II, the diaphragm tends to roll against the cylinder wall and to move the follower and push rod to the right against the action of the spring 24, and on connection of the push rod 2| with a suitable brake actuator, not shown, the brakes maybe applied and released in accordance with the application and release of fluid pressure to and from the left end of the casing. The actuator may be mounted a in any suitable manner on the vehicle, and in the present embodiment of the invention, mounting studs 26 are threadedly received by the cover plate and provided with nuts 2'! adapted to clamp the cover plate to a suitablebracket such as that 7 indicated at 28.

It will be understood from the foregoing description that an actuator has been provided so constructed that means have been provided for insuring proper positioning of the diaphragm in the casing during assembly in order to provide uniform clamping of the diaphragm between the clamping rin and the left end of the casing for the purpose of insuring that each portion of the diaphragm will be subjected to its proper share of the stress imposed when fluid pressure is admitted to the left end of the casing, and at the same time the stop l6 serves to limit the degree of compression of the diaphragm and of the lugs 6 to any desired value. Due to the fact that the lugs 6 are turned inward with respect to the longitudinal center line of the actuator, the outside diameter of the actuator is only slightly greater than the diameter of the diaphragm which determines its effective area. It is well known that the space available for mounting actuators of this type on the axles on motor vehicles is extremely limited, and the present invention provides means for obtaining a relatively large output and a relatively long stroke from an actuator of the diaphragm type, while at the same time maintaining the outside diameter at a value which permits installation of the actuator on vehicles having a minimum of space available for this purpose.

While the invention has been illustrated and described herein with considerable particularity,

it is to be specifically understood that the same is not limited to the form shown,.but may receive a variety of mechanical expressions, as will now readily appear to those skilled in the art. Reference will, therefore, be had to the appended claims for a definition of the limits of the invenv the other end thereof, an end wall for closing said other end, a port in said end wall for the admission of fluid pressure, a cup-shaped flexible diaphragm having a closed bottom portion and a side wall formed with integral individual lugs extending outwardly therefrom adjacent the open end of the diaphragm, a portion of the side wall adjacent said open end being folded over the outside of the remainder of the side wall so that the lugs extend inwardly over the outside of said bottom portion, a clamping member interposed between the outer surface of said bottom portion and lugs and having a tapered surface adapted to engage the wall of the diaphragm adjacent said lugs, means for fastening the clamping member to the end wall of the casing for clamping said lugs between the member and end wall and for clamping a portion of the diaphragm side wall between the tapered surface of said clamping member and the tapered portion of said casing, and a follower member positioned in the casing in,'engagement with the inner surface of said closed bottom portion of the diaphragm.

2. A fluid pressure actuator comprising a casinl having a cylindrical bore open at one endand having an inwardly tapered portion adjacent the other end thereof, an'end wall for closing said other end, a port in said end wall for the admission of fluid pressure, a cup-shaped flexible diaphragm having a closed bottom portion and a side wall formed with integral individual lugs extending outwardly therefrom adjacent the open end of the diaphragm, a portion of the side wall adiacent said open end being folded over the outside of the remainder of the side wall so that the lugs extend inwardly over the outside of said bottom portion, a clamping member interposed between the outer surface of said bottom portion and lugs and having a tapered surface adapted to engage the wall of the diaphragm adjacent said lugs, means for fastening the clamping member to the end wall of the casing for clamping said lugs between the member and end wall and for clamping a portion of the diaphragm side wall between the tapered surface of said clamping member and the tapered portion of said casing, and a cylindrical follower member positioned in the casing having one end thereof in engagement with the inner surface of the closed bottom portion of the diaphragm and the cylindrical sur face thereof in engagement with the inner wall of the unfolded portion of the diaphragm adjacent the closed bottom portion thereof.

3. A fluid pressure actuator comprising a casing having a cylindrical bore open at one end and having an inwardly tapered portion adjacent the other end thereof, an end wall for closing said other end, a port in said end wall for the admis side wall formed with integral individual lugs extending outwardly therefrom adjacent the open end of the diaphragm, a portion of the side wall adjacent said open end bein folded over the outside of the remainder of the side wall so that the lugs extend inwardly over the outside of said bottom portion, a clamping member interposed between the outer surface of said bottom portion and lugs and having a tapered surface adapted to engage the wall of the diaphragm adjacent said lugs, means for fastening the clampin memher to th end wall of the casing for clamping said lugs between the member and end wall and for clamping a portion of the diaphragm side wall between the tapered surface of said clamping member and the tapered portion of said casing, a cylindrical follower member positioned in the casing having one end thereof in engagement with the inner surface of said closed bottom portion of the diaphragm, a closure member attached to the casing for closing the open end of said bore and provided with an opening, a push rod extending through said opening and having one end operatively connected with said follower member, and resilient means interposed between said last-named closure member and follower member for urging the latter toward the end wall of said bore.

4. A fluid pressure actuator comprising a casing having a cylindrical bore open at one end and having an inwardly tapered portion adjacent the other end thereof, an end wall for closing said other end, a port in said end wall for the admission of fluid pressure, a cup-shaped flexible diaphragm having a closed bottom portion and a side wall formed with integral individual ported lugs extending outwardly therefrom adjacent the open end of the diaphragm, a portion of the side wall adjacent said open end being folded over the outside of the remainder of the side wall so that the lugs extend inwardly over the outside of said bottom portion, a cylindrical follower member positioned in the casing having one end in engagement with the inner surface of the closed bottom portion of the diaphragm, and means for positioning said diaphragm in said casing and for clamping a portion of the diaphragm in sealing engagement with the tapered portion of, said casing includin a plurality of openings in the end wall of said casing, a clamping member interposed between said lugs and the outer surface of said bottom portion of the diaphragm having a tapered portion adapted to engage the wall of the diaphragm adjacent said lugs, and clamping means carried by said clamping member adapted to register with the ports in said lugs and the openings in said end wall and operable for moving the clamping member toward said end wall.

5. A fluid pressure actuator comprising a casing having a cylindrical-bore open at one end and having an inwardly tapered portion adjacent the other end thereof, an end wall for closing said other end, a port in said end wall for the admission of fluid pressure, a cup-shaped flexible diaphragm having a closed bottom portion and a side wall formed with integral individual ported lugs extending outwardly therefrom adjacent the open end of the diaphragm, a portion of the side wall adjacent said open end being folded over the outside-of the remainder of the side wall so that the lugs extend inwardly over the outside of said bottom portion, a cylindrical follower member positioned in the casing having one end in engagement with the inner surface of the closed bottom portion of the diaphragm, and means for positioning said diaphragm in said casing and for clamping a portion of the diaphragm in sealing engagement with the tapered. portion of said casing including a plurality of openings in the end wall of said casing, a clamping member interposed between said lugs and the outer surface of said bottom portion of the diaphragm having a tapered portion adapted to engage the wall of 'the diaphragm adjacent said lugs, clamping means carried by said clamping member adapted to register with the ports in said lugs and the openings in said end wall and operable for moving the clamping member toward said end wall, and means for limiting the degree of movement of said clamping member by said clamping means whereby the degree of compression of the diaphragm between the clamping member and casing is correspondingly limited.

6. A fluid pressure actuator comprising a casing having a cylindrical bore open at one end and havingan inwardly tapered portion adjacent the other end thereof, an end wall for closing said other end, a port in said end wall for the admission of fluid pressure, a cup-shaped flexible diaphragm having a closed bottom portion and a side wall formed with integral individual ported lugs extending outwardly therefrom adjacent the open end .of the diaphragm, a portion of the side wall adjacent said open end being folded over the outside of the remainder of the side wall so that the lugs extend inwardly over the outside of said bottom portion, a cylindrical follower member positioned in the casing having one end in engagement with the inner surface of the closed bottom portion of the diaphragm, and means for positioning said diaphragm in said casing and for clamping a portion of the diaphragm in sealing engagement with the tapered portion of said casing including a plurality .of openings in the end wall of said casing, a clamping member interposed between said lugs and the outer surface of said bottom portion of the diaphragm having a tapered portion adapted to engage the wall of the diaphragm adjacent said lugs, and a portion adapted to engage the inner surface of the lugs, and clamping means carried by the clamping member adapted to register with and extend through the ports in said lugs and the openings in said end wall and operable for moving the clamping member toward said end wall, whereby a portion of the diaphragm is clamped in sealing engagement with the tapered portion of said casing and the lugs are clamped against the inner surface of said end wall to prevent leakage of fluid pressure through said last named ports.

'I. A fluid pressure actuator comprising a casing having a bore open at one end and having an inwardly extending portion at the other end thereof, an end wall for closing said other end, a port in said end wall for the admission of fluid pressure, a cup-shaped flexible diaphragm having a closed bottom portion and a side wall formed with integral individual lugs extending outwardly therefrom adjacent the open end of the diaphragm, a portion of the side wall adjacent the open end of the diaphragm being folded over the outside of the remainder of the side wall so that the lugs extend inwardly over the outside surface of said bottom portion, a clamping member interposed between the outer face of said bottom portion and said lugs and having a clamping surface adapted to engage the wall of the diaphragm adjacent said lugs, means engaging said lugs, clamping member and end wall for positioning the diaphragm and clamping member in the casing, means associated with the last named means for urging the clamping member toward said end wall whereby the wall of the diaphragm adjacent said lugs is clamped in sealing engagement with said inwardly extending portion of said casing, and a follower mounted in the casing having one end in engagement with the inner surface of the closed bottom portion of said diaphragm.

8. A fluid pressure actuator comprising a casing having a bore open at one end and'having an inwardly extending portion at the other end' thereof, an end wall for closing said other end,

a port in said end wall for the admission of fluid pressure, a cup-shaped flexible diaphragm having a closed bottom portion and an outwardly flared portion at its open end, a portion of the side wall adjacent the open end being folded back over the remainder of the side wall so that said flared portion extends inwardly from the folded side wall, a clamping 'member adapted to engage the inwardly extending flared portion to position the diaphragm with respect to the casing, means for positioning the clamping member in the casing adjacent said iend wall, means for urging said clamping meniber toward said end wall, whereby the inwardly extending flared portion of the diaphragm is clamped in sealing engagement with the surface offthe inwardly extending portion of the casing, and a follower member positioned in the casing having one end adapted to engage the inner surface of the closed bottom portion of said diaphragm.

9. A fluid pressure actuator comprising a casing having a bore open at one end and having an inwardly extending portion at the other end thereof, an end wall for closing said other end, a port in said end wall for the admission of fluid pressure, a cup-shaped flexible diaphragm having a closed bottom portion and a side wall having a continuous raised bead formed on one surface thereof adjacent to the open end of the diaphragm and integral individual lugs extending outwardly from the side wall at the open end of the diaphragm, a portion of the side wall adjacent the open end of the diaphragm being folded over the outside of the remainder of the side wall so that the lugs extend inwardly over the outside surfaceof said bottom portion, a clamping member interposed between the outer surface of said bottom portion and lugs and having a clamping surface adapted to engage the inner surface of the folded over portion of the side wall adjacent said bead, means engaging said lugs, clamping member and end wall for positioning the diaphragm and clamping member in the casing, a follower positioned in the casing having one end in engagement with the inner surface of the closed bottom portion of the diaphragm, and means for urging the clamping member toward the end wall of the casing, whereby said bead is compressed and the portion of the side wall adjacent thereto is clamped in sealing engagement with the surface of the inwardly extending portion of the casing.

10. A fluid pressure actuator comprising a casing having a bore open at one end and having an inwardly extending portion adjacent the other end, an end wall for closing said other end, a port in said end wall for the admission of fluid pressure to the casing, a flexible tapered diaphragm having one end of smaller diameter than the other end, said other end being formed with an outwardly flared portion and the side wall of the diaphragm adjacent the flared portion being folded back over the outside of the remainder of the side wall so that said flared portion extends inwardly from the folded side wall, said end of the diaphragm of smaller diameter being closed, a clamping member adapted to engage the inwardly extending flared portion to position the diaphragm with relation to the casing, means for positioning the clamping member in the casing adjacent said end wall, means for urging said clamping member toward said end wall whereby the inwardly extending flared portion of the diaphragm is clamped in sealing engagement with the surface of the inwardly extending portion of said casing, a cover plate attached to the casing to close the open end of the bore, a follower member in operative engagement with said one end of the diaphragm and adapted to engage and support the adjacent side wall of the diaphragm, a centrally located bore in said cover plate, a push rod connected with said follower member and extending through saidbore in the cover plate, and resilient means interposed between said cover plate and follower member for urging the follower member and said one end of the diaphragm toward the end wall of said bore.

11. A fluid pressure actuator comprising a casing having one end open and provided with an inwardly extending portion adjacent the other end, an end wall for closing said other end, said wall having a fluid admission port, a flexible tapered diaphragm having one endof smaller diameter than the other end, the latter end being formed with an outwardly extending portion and the side wall of the diaphragm adjacent said portion being folded back over the outside of the remainder of the side wall so that the outwardly extending portion extends inwardly from the folded side wall, said end of the diaphragm of smaller diameter being closed, a clamping member having a portion engaging the inwardly extending portion to position the diaphragm with relation to the casing, means for securing the clamping member to said end wall with said inwardly extending portion of the diaphragm clamped in sealing engagement with the surface of the inwardly extending portion of the casing, a cover plate attached to the casing to close the open end of the casing, a follower member in operative engagement with said one end of the diaphragm and formed with a cylindrical part engaging and supporting the adjacent side wall of the diaphragm, said plate being provided with an opening, an actuated member connected with said follower member and extending through the opening in the cover plate, and resilient means interposed between said cover plate and follower member for normally urging the follower member and said one end of the diaphragm toward the end wall of, said casing.

12. A fluid pressure actuator comprising a casing having one end open and provided with an inwardly tapered portion adjacent the other end thereof, an end wall closing said other end and provided with a fluid admission port, a flexible tapered diaphragm having one end of smaller diameter than the other end, the latter end being formed with an outwardly extending portion and the side wall of the diaphragm adjacent said portion being folded back over the outside of the remainder of the side wall so that the outwardly extending portion extends inwardly from the folded side wall, said end of the diaphragm of smaller diameter being closed, a follower member in operative engagement with said one end of the diaphragm, and means for positioning the diaphragm in said casing and for clamping the inwardly extending portion of the diaphragm in sealing engagement with the tapered portion of the casing including a clamping member having a portion engaging the inwardly extending portion of the diaphragm, and means for securing said clamping member to said end. wall of said casing.

13. A fluid pressure actuator as set forth in claim 12 which comprises in addition, means carried by said clamping member and cooperating with said end wall of said casing for limiting the movement of said member toward said end wall of said casin to correspondingly limit the compression of the diaphragm between the clamping member and the tapered portion of the casing.

14. A fluid pressure actuator comprising a casing having one end open and provided adjacent its other end with an inwardly tapered portion, said other end having an end wall provided with an opening therein, a flexible tapered diaphragm having one end of smaller diameter than the other end, the latter end being formed with an outwardly extending portion and the side wall of the diaphragm adjacent said portion being folded back over the outside of the remainder of the side wall so that the outwardly extending portion extends inwardly from the folded side wall, said end of the diaphragm of smaller diameter being closed, cover means for the open end of the casing, an actuated member operatively connected with the closed end of the diaphragm and provided with a part extending through the cover means, means for positioning the diaphragm in the casing and for clamping the inwardly extending portion of the diaphragm in sealing engagement with the taperedportion of the casing including a cup-shaped clamping member having a portion engaging the inwardly extending portion of the diaphragm, and means for securing the clamping member to said end wall of said casing, said clamping member having a part engaging the end wall of said casing for limiting the movement of said member upon operation of said securing means to correspondingly limit the compresison of the porton of the diaphragm between the clamping member and the tapered portion of the casing.

ELLERY R. FITCH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,806,360 Moller May 19, 1931 1,809,491 Rowell June 9, 1931 2,125,262 Hennecke July 26, 1938 2,178,953 Chilton Nov. 7, 1939 2,241,056 Chilton May 6, 1941 2,320,191 Mott May 25, 1943 FOREIGN PATENTS Number Country Date 584,025 Germany 1939 704,479 France 1931 

